This invention relates generally to electrified monorails, and more particularly to communicating information from a device located off-board the electrified monorail to the vehicles that travel on the monorail. The term xe2x80x9celectrified monorailxe2x80x9d is intended to be used expansively, including systems that support carriers on more than one rail.
Electrified monorails are widely used in manufacturing environments today for transporting products throughout manufacturing plants and other types of buildings. The electrified monorails may be overhead electrified monorails, in which the rails are elevated and vehicles carry the product underneath the rails, or they may be skillet-type monorails, in which the rails are positioned on the floor and the skillets travel over the rails and support the product from underneath. In either situation, it is often desirable to be able to communicate information from an off-board source to one or more individual vehicles traveling on the electrified monorail. Such information may include speed, height, or position commands that dictate the speed of the vehicle and the height or position of the product being carried by the vehicle. Other types of information may also desirably be communicated to the vehicle, such as zone blocking information and the like.
In the past, the communication of such information to the vehicle has involved the use of proprietary communication systems. Such proprietary systems include an off-board communications module which is connected to at least one of the rails of the electrified monorail system, along with one or more communications modules located on the individual vehicles that are in electrical contact with the at least one communication rail. Because these proprietary communications systems use specialized electronics that are proprietary to a particular vendor, there is often a reluctance by system users to adopt such communications systems for fear the vendor may discontinue support of the product in the future. Such proprietary systems also tend to tie a system user to a particular vendor for service and upgrades, which is often undesirable for companies wishing to ensure multiple sources for their electrified monorail communications needs. Accordingly, a need exists for a simple electrified monorail communications system that does not tie a purchaser to a particular vendor or a specialized technology.
Accordingly, the present invention provides a communications system that generally uses standard, off-the-shelf components, that are widely known and used, thereby freeing potential customers from being dependent upon a particular vendor for products and maintenance. According to one aspect of the present invention, a communications system for an electrified monorail having at least one electrically conductive buss bar and a vehicle is provided. The communications system includes a first programmable logic controller having an output adapted to be electrically coupled to at least one electrically conductive buss bar. The output is capable of assuming more than one state. The first programmable logic controller is programmed to sequentially set its output at a series of different states corresponding to a message. A second programmable logic controller is also provided and includes an input adapted to be electrically coupled to the at least one electrically conductive buss bar. The second programmable logic controller is programmed to store in memory the series of different states output from the first programmable logic controller.
According to another aspect of the present invention, an electrified monorail system is provided that includes an electrified monorail with at least one buss bar, at least one carrier adapted to move on the electrified monorail, and a first and a second programmable logic controller. The first programmable logic controller includes an output electrically coupled to the buss bar. The output is capable of assuming more than one state such that a series of different states are output onto the buss bar. The series of different states correspond to a message. A second programmable logic controller is also provided and includes an input electrically coupled to the buss bar. The second programmable logic controller is located on the carrier and is programmed to store in memory the series of different states output from the first programmable logic controller.
According to yet another aspect of the present invention, a method is provided for transmitting information over a buss bar in an electrified monorail system. The method includes providing a first programmable logic controller with at least one output and a second programmable logic controller with at least one input. The output of the first programmable logic controller and the input of the second programmable logic controller are coupled to the buss bar. The first programmable logic controller is programmed to output a series of different states corresponding to the information onto the buss bar. The second programmable logic controller is programmed to detect the series of different states output onto the buss bar and at least temporarily store them in a memory in the second programmable logic controller.
The present invention provides a simple, reliable communications system for electrified monorails. Because the system is made up of off-the-shelf programmable logic controllers, customers of the communications system are not locked into any particular vendor for supplying the communications system. Further, because the communications system relies upon programmable logic controllers, which are widespread and well known, most customers can implement and maintain the communications system without specialized service personnel from the vendor. Additionally, the use of programmable logic controllers provides a more inexpensive communications solution than prior systems. These and other advantages of the present invention will be apparent to one skilled in the art in light of the following specification when read in conjunction with the accompanying drawings.